The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
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What Is the Highest Mounjaro Dose in the UK?
The highest available dose of Mounjaro (tirzepatide) in the UK is 15 mg, administered once weekly by injection. This maximum dose is reached gradually through a structured dose titration schedule, starting at 2.5 mg and increasing every four weeks. Not all patients require or reach the maximum dose — your prescriber will assess the appropriate level based on your individual response and health needs. Understanding the full dose range and titration process helps you know what to expect from treatment.
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Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
Mounjaro Dose Titration Schedule and Maximum Dose
Mounjaro is available in five incremental doses, escalating over approximately 20 weeks to reach the 15 mg maximum. Each dose is a once-weekly injection delivered via the Mounjaro KwikPen:
- 2.5 mg weeks 1–4 (starting dose)
- 5 mg weeks 5–8 (first escalation)
- 7.5 mg weeks 9–12
- 10 mg weeks 13–16
- 12.5 mg weeks 17–20
- 15 mg week 21 onwards (maximum maintenance dose)
Your prescriber must wait a minimum of four weeks at each dose before increasing further. This gradual dose titration approach allows your body to adapt and helps minimise side effects such as nausea or gastrointestinal discomfort. Some patients respond well at lower doses (5 mg or 10 mg) and do not need to escalate further — clinical trials show weight loss benefit at all dose levels.
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How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
NHS Prescribing and Individual Assessment
In the UK, Mounjaro is prescribed through NHS specialist tier 3 weight management services following referral from your GP, or through private online prescribing following a clinical assessment. Your prescriber will determine whether you should reach the maximum 15 mg dose or stabilise at a lower level based on your individual response, any weight loss achieved, and your tolerance of side effects. Use our free GLP-1 weight loss calculator to estimate potential outcomes at different doses. Mounjaro vs Wegovy discussions often compare maximum doses — note that Mounjaro reaches 15 mg whereas Wegovy (semaglutide) reaches a maximum of 2.4 mg, reflecting their different mechanisms of action.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Do I need to reach the 15 mg maximum dose?
No. Your prescriber will assess the optimal dose for you based on weight loss response, side effects, and health goals. Many patients achieve their target weight loss at 10 mg or lower. The maximum dose is available if needed, but not required for everyone.
What happens if I can't tolerate the dose escalation?
If you experience intolerable side effects at a particular dose, your prescriber may pause escalation or reduce to the previous dose. Dose titration is flexible and individualised — always discuss any concerns with your healthcare provider.
How long does it take to reach the highest Mounjaro dose?
It takes approximately 20 weeks (5 months) of once-weekly injections to reach the 15 mg maximum dose, assuming you escalate at each four-week interval. Some patients stabilise at lower doses and do not continue escalating.
Is the 15 mg dose available through the NHS in the UK?
Yes, the 15 mg dose is available through NHS specialist weight management services following NICE approval of tirzepatide for weight management. However, NHS access varies by region and availability, and waiting lists can be lengthy in many areas.
What does "dose titration" mean with Mounjaro?
Dose titration is the gradual increase in medication strength over time. With Mounjaro, you start at 2.5 mg and increase by small increments every four weeks, allowing your body to adjust and helping reduce side effects.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.